Mexico has around 8 million migrants stateside, compared to 100,000 or so North Koreans illegally in China. Mexico's population is five times that of the North's, so adjusted for population Mexico has lost 16 times as many people to illegal emigration to the US as North Korea has lost to China. There are, of course, big differences, namely that Mexicans fleeing Mexico are celebrated by the Mexican government, while North Koreans fleeing North Korea risk severe punishment if captured and returned home.

I'm a bit confused. If we make the US-Mexico border airtight, the Mexican government will collapse (a bad thing). But if the China-Korea border is sealed up, Kim Jong Il's regime will live on in perpetuity (another bad thing).